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  • 1.
    Abdulla, Hind
    et al.
    Khalifa Univ Sci & Technol, Engn Syst & Management, POB 127788, Abu Dhabi, U Arab Emirates.;Khalifa Univ Sci & Technol, Adv Digital & Addit Mfg Ctr, POB 127788, Abu Dhabi, U Arab Emirates..
    An, Heungjo
    Kumoh Natl Inst Technol, Sch Ind Engn, Gumi 39177, South Korea..
    Barsoum, Imad
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. Khalifa Univ Sci & Technol, Adv Digital & Addit Mfg Ctr, POB 127788, Abu Dhabi, U Arab Emirates.;Khalifa Univ Sci & Technol, Mech Engn, POB 127788, Abu Dhabi, U Arab Emirates..
    Maalouf, Maher
    Khalifa Univ Sci & Technol, Engn Syst & Management, POB 127788, Abu Dhabi, U Arab Emirates.;Khalifa Univ Sci & Technol, Res Ctr Digital Supply Chain & Operat, POB 127788, Abu Dhabi, U Arab Emirates..
    Mathematical Modeling of Multi-Performance Metrics and Process Parameter Optimization in Laser Powder Bed Fusion2022In: Metals, ISSN 2075-4701, Vol. 12, no 12, article id 2098Article in journal (Refereed)
    Abstract [en]

    This study aims to develop mathematical models to improve multi-performance metrics, such as relative density and operating costs, in laser powder bed fusion (LPBF), also known as selective laser melting, a metallic additive manufacturing technique, by optimizing the printing process parameters. The work develops a data-driven model for relative density based on measurements and an analytical model for operating costs related to the process parameters. Optimization models are formulated to maximize relative density or minimize operating costs by determining the optimal set of process parameters, while meeting a target level of the other performance metrics (i.e., relative density or operating costs). Furthermore, new metrics are devised to test the sensitivity of the optimization solutions, which are used in a novel robust optimization model to acquire less sensitive process parameters. The sensitivity analysis examines the effect of varying some parameters on the relative density of the fabricated specimens. Samples with a relative density greater than 99% and a machine operating cost of USD 1.00 per sample can be produced, utilizing a combination of low laser power (100 W), high scan speed (444 mm/s), moderate layer thickness (0.11 mm), and large hatch distance (0.4 mm). This is the first work to investigate the relationship between the quality of the fabricated samples and operating cost in the LPBF process. The formulated robust optimization model achieved less sensitive parameter values that may be more suitable for real operations. The equations used in the models are verified via 10-fold cross-validation, and the predicted results are further verified by comparing them with the experimental data in the literature. The multi-performance optimization models and framework presented in this study can pave the way for other additive manufacturing techniques and material grades for successful industrial-level implementation.

  • 2. Ahmed, Hesham
    et al.
    Morales-Estrella, R.
    Viswanathan, Nurin
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gas-Solid Reaction Route toward the Production of Intermetallics from Their Corresponding Oxide Mixtures2016In: Metals, ISSN 2075-4701, Vol. 6, no 8, article id 190Article in journal (Refereed)
    Abstract [en]

    Near-net shape forming of metallic components from metallic powders produced in situ from reduction of corresponding pure metal oxides has not been explored to a large extent. Such a process can be probably termed in short as the "Reduction-Sintering" process. This methodology can be especially effective in producing components containing refractory metals. Additionally, in situ production of metallic powder from complex oxides containing more than one metallic element may result in in situ alloying during reduction, possibly at lower temperatures. With this motivation, in situ reduction of complex oxides mixtures containing more than one metallic element has been investigated intensively over a period of years in the department of materials science, KTH, Sweden. This review highlights the most important features of that investigation. The investigation includes not only synthesis of intermetallics and refractory metals using the gas solid reaction route but also study the reaction kinetics and mechanism. Environmentally friendly gases like H-2, CH4 and N-2 were used for simultaneous reduction, carburization and nitridation, respectively. Different techniques have been utilized. A thermogravimetric analyzer was used to accurately control the process conditions and obtain reaction kinetics. The fluidized bed technique has been utilized to study the possibility of bulk production of intermetallics compared to milligrams in TGA. Carburization and nitridation of nascent formed intermetallics were successfully carried out. A novel method based on material thermal property was explored to track the reaction progress and estimate the reaction kinetics. This method implies the dynamic measure of thermal diffusivity using laser flash method. These efforts end up with a successful preparation of nanograined intermetallics like Fe-Mo and Ni-W. In addition, it ends up with simultaneous reduction and synthesis of Ni-WN and Ni-WC from their oxide mixtures in single step.

  • 3.
    Ai, Songyuan
    et al.
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Long, Mujun
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Zhang, Siyuan
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Chen, Dengfu
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Dong, Zhihua
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Liu, Peng
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Zhang, Yanming
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Duan, Huamei
    Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Coal Mine Disaster Dynam & Control, Chongqing 400044, Peoples R China.;Chongqing Univ, Chongqing Key Lab Vanadium Titanium Met & New Mat, Chongqing 400044, Peoples R China..
    Ab Initio Calculations on Elastic Properties of IF Steel Matrix Phase at High Temperature Based on Lattice Expansion Theory2020In: Metals, ISSN 2075-4701, Vol. 10, no 2, article id 283Article in journal (Refereed)
    Abstract [en]

    Elucidating the evolution law of the elastic properties of the matrix phase is of great significance for the control of steel properties and quality during continuous casting and subsequent heat treatment. In this paper, thermal expansion experiments and ab initio calculations are used to study the elastic properties of the interstitial free (IF) steel matrix phase in different magnetic states and crystal structures. The results show that the bulk modulus B and the tetragonal shear elastic constant C' for the entire temperature range decrease with increasing temperature, but C-44 is the opposite. While from paramagnetic (PM) to ferromagnetic (FM) state, C'(C-44) have changed similar to 188% (similar to 27%), B increases by similar to 55% during the crystal structure change (fcc -> bcc). With the FM to PM state, the Zener anisotropy parameter increases sharply, and Young's modulus decreases significantly in the [001] direction; the maximum difference is similar to 76 GPa. The evolution rate of average Young's modulus in single bcc-phase FM (fcc-phase PM) range reaches similar to 5.5(similar to 5.6) x 10(-2) GPa K-1. The research provides an effective method for ab initio calculation of the elastic properties of interstitial free and ultra-low carbon steels at high temperature, also furnishing a basis for the application of ab initio calculations to the high temperature performance of steel materials.

  • 4.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sheng, Dong-yuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    A Computational Fluid Dynamics Study on Physical Refining of Steel Melts by Filtration2023In: Metals, ISSN 2075-4701, Vol. 13, no 6, article id 1022Article in journal (Refereed)
    Abstract [en]

    In this paper, a previous experimental investigation on physical refining of steel melts by filtration was numerically studied. To be specific, the filtration of non-metallic alumina inclusions, in the size range of 1-100 & mu;m, was stimulated from steel melt using a square-celled monolithic alumina filter. Computational fluid dynamics (CFD) studies, including simulations of both fluid flow and particle tracing using the one-way coupling method, were conducted. The CFD predicted results for particles in the size range of & LE;5 & mu;m were compared to the published experimental data. The modeled filtration setup could capture 100% of the particles larger than 50 & mu;m. The percentage of the filtered particles decreased from 98% to 0% in the particle size range from 50 & mu;m to 1 & mu;m.

  • 5.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Sheng, Dongyuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Effect of Batch Dissimilarity on Permeability of Stacked Ceramic Foam Filters and Incompressible Fluid Flow: Experimental and Numerical Investigation2022In: Metals, ISSN 2075-4701, Vol. 12, no 6, p. 1001-, article id 1001Article in journal (Refereed)
    Abstract [en]

    Ceramic foam filters (CFFs) are used to remove inclusions and/or solid particles from molten metal. In general, the molten metal poured on the top of a CFF should reach a certain height to form the pressure (metal head) required to prime the filter. For estimating the required metal head and obtaining the permeability coefficients of the CFFs, permeability experiments are essential. Recently, electromagnetic priming and filtration of molten aluminum with low and high grades of CFF, i.e., 30, 50 and 80 pore per inch (PPI) CFFs, have been introduced. Since then, there has been interest in exploring the possibility of obtaining further inclusion entrapment and aluminum refinement by using electromagnetic force to prime and filter with stacked CFFs. The successful execution of such trials requires a profound understanding concerning the permeability parameters of the stacked filters. Such data were deemed not to exist prior to this study. As a result, this study presents experimental findings of permeability measurements for stacks of three 30, three 50 and three 80 PPI commercial alumina CFFs from different industrial batches and compares the findings to numerically modelled data as well as previous research works. Both experimental and numerical findings showed a good agreement with previous results. The deviation between the experimentally and numerically obtained data lies in the range of 0.4 to 6.3%.

  • 6.
    Alekseeva, Ekaterina
    et al.
    Peter Great St Petersburg Polytech Univ, Sci & Technol Complex New Technol & Mat, Inst Adv Engn Technol, Polytech Skaya 29, St Petersburg 194064, Russia..
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Alkhimenko, Aleksey
    Peter Great St Petersburg Polytech Univ, Sci & Technol Complex New Technol & Mat, Inst Adv Engn Technol, Polytech Skaya 29, St Petersburg 194064, Russia..
    Effect of Inclusions on the Corrosion Properties of the Nickel-Based Alloys 718 and EP7182020In: Metals, ISSN 2075-4701, Vol. 10, no 9, article id 1177Article in journal (Refereed)
    Abstract [en]

    Inclusions in steels and alloys are known to lower the resistance to deformation, as well as to lower the mechanical, corrosion and other properties. Studies of inclusions in nickel-based alloys are important since these materials could suffer from corrosion degradation in harsh operational conditions. This, in fact, could lead to a pitting initiation around the inclusions. Two industrial Ni-based alloys (alloy 718 and EP718) were investigated to determine the harmful effects of different inclusions on the corrosion resistance of Ni-based alloys. Specifically, the inclusion characteristics (such as composition, morphology, size, number and location) were determined for inclusions collected on film filters after electrolytic extraction and dissolution of a metal matrix around different inclusions on surfaces of metal samples after electrolytic extraction (EE). It was found that both Ni-based alloys contain various inclusion types: carbides (large size NbTi-C and small multicomponent carbides), nitrides TiNb-N and sulphides (TiNb-S in EP718 alloy). The most harmful effects on the corrosion resistance of metal were detected around sulphides and small carbides containing Mo, W, Cr. Dissolution effects were also observed around large carbides and nitrides, especially around inclusions larger than 10 mu m. Moreover, the dissolution of a matrix around inclusions and clusters located on the grain boundaries were found to be 2.1-2.7 times larger compared to inclusions found inside of grains of the given alloy samples.

  • 7.
    Al-Saadi, Munir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process. Sandvik Materials Technology AB.
    Mu, Wangzhong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Hulme-Smith, Christopher
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Sandberg, Fredrik
    Sandvik Materials Technology AB.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation2021In: Metals, ISSN 2075-4701, Vol. 11, no 1, article id 36Article in journal (Refereed)
    Abstract [en]

    Alloy 825 is widely used in several industries, but its useful service life is limited by both mechanical properties and corrosion resistance. The current work explores the effect of the addition of magnesium on the recrystallization and mechanical behavior of alloy 825 under hot compression. Compression tests were performed under conditions representative of typical forming processes: temperatures between 1100 and 1250 °C and at strain rates of 0.1–10 s−1 to a true strain of 0.7. Microstructural evolution was characterized by electron backscattered diffraction. Dynamic recrystallization was found to be more prevalent under all test conditions in samples containing magnesium, but not in all cases of conventional alloy 825. The texture direction ⟨101⟩ was the dominant orientation parallel to the longitudinal direction of casting (also the direction in which the samples were compressed) in samples that contained magnesium under all test conditions, but not in any sample that did not contain magnesium. For all deformation conditions, the peak stress was approximately 10% lower in material with the addition of magnesium. Furthermore, the differences in the peak strain between different temperatures are approximately 85% smaller if magnesium is present. The average activation energy for hot deformation was calculated to be 430 kJ mol−1 with the addition of magnesium and 450 kJ mol−1 without magnesium. The average size of dynamically recrystallized grains in both alloys showed a power law relation with the Zener–Hollomon parameter, DD~Zn, and the exponent of value, n, is found to be 0.12. These results can be used to design optimized compositions and thermomechanical treatments of alloy 825 to maximize the useful service life under current service conditions. No experiments were conducted to investigate the effects of such changes on the service life and such experiments should now be performed.

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  • 8.
    Arzpeyma, Niloofar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Kobolde & Partners AB, S-11860 Stockholm, Sweden..
    Alam, Moudud
    Dalarna Univ, Sch Informat & Engn, S-79188 Falun, Sweden..
    Gyllenram, Rutger
    Kobolde & Partners AB, S-11860 Stockholm, Sweden..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Model Development to Study Uncertainties in Electric Arc Furnace Plants to Improve Their Economic and Environmental Performance2021In: Metals, ISSN 2075-4701, Vol. 11, no 6, article id 892Article in journal (Refereed)
    Abstract [en]

    A statistical model is developed in order to simulate the melt composition in electric arc furnaces (EAFs) with respect to uncertainties in (1) scrap composition, (2) scrap weighing and (3) element distribution factors. The tramp element Cu and alloying element Cr are taken into account. The model enables simulations of a charge program as well as backwards estimations of the element concentrations and their variance in scrap. In the backwards calculation, the maximum likelihood method is solved by considering three cases corresponding to the involved uncertainties. It is shown that the model can estimate standard deviations for elements so that the real values lie within the estimated 95% confidence interval. Moreover, the results of the model application in each target product show that the estimated scrap composition results in a melt composition, which is in good agreement with the measured one. The model can be applied to increase our understanding of scrap chemical composition and lower the charged material cost and carbon footprint of the products.

  • 9.
    Arzpeyma, Niloofar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Mathematical Modeling of Postcombustion in an Electric Arc Furnace (EAF)2019In: Metals, ISSN 2075-4701, Vol. 9, no 5, article id 547Article in journal (Refereed)
    Abstract [en]

    Numerical modeling was used to study the capability of postcombustion in an electric arc furnace (EAF) equipped with virtual lance burners. The CO flow rate at the molten bath surface was estimated using the off-gas data obtained close to the outlet of an EAF. Then, the effect of the secondary oxygen flow rate on postcombustion was studied. The results show a CO flow rate of 0.6 kgs(-1) and 0.8 kgs(-1) for operation modes of burner and burner + lancing. Increase of the secondary oxygen flow rates of 60% and 70% result in 17% and 7% increase in the postcombustion ratio (PCR) for the burner and burner lancing modes, respectively.

  • 10.
    Arzpeyma, Niloofar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Kobolde & Partners AB, Stockholm 11860, Sweden.
    Gyllenram, Rutger
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Kobolde & Partners AB, Stockholm 11860, Sweden.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Development of a Mass and Energy Balance Model and Its Application for HBI Charged EAFs2020In: Metals, ISSN 2075-4701, Vol. 10, no 3, article id 311Article in journal (Refereed)
    Abstract [en]

    A static mass and energy balance model combined with a MgO saturation slag model is developed for electric arc furnaces. The model parameters including distribution ratios and dust factors are calibrated for a specific furnace using experimental data. Afterward, the model is applied to study the effect of charging different amounts of hot briquetted iron (HBI) on energy consumption, charged slag former amount, and slag composition. The following results were obtained per each 1% increase of HBI additions: (i) a 0.16 Nm(3)/t decrease in the amount of injected oxygen for metal oxidation, (ii) a 1.29 kWh/t increase in the electricity consumption, and (iii) a 34 kg increase in the amount of the slag.

  • 11.
    Balachandran, Srija
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Lemaître, Tom
    Department of Chemistry and Chemical Engineering, Industrial Materials Recycling and Nuclear Chemistry, Chalmers University of Technology.
    Vieceli, Nathália
    Department of Chemistry and Chemical Engineering, Industrial Materials Recycling and Nuclear Chemistry, Chalmers University of Technology.
    Lombardo, Gabriele
    Department of Chemistry and Chemical Engineering, Industrial Materials Recycling and Nuclear Chemistry, Chalmers University of Technology.
    Petranikova, Martina
    Department of Chemistry and Chemical Engineering, Industrial Materials Recycling and Nuclear Chemistry, Chalmers University of Technology.
    Comparative Study for Selective Lithium Recovery via Chemical Transformations during Incineration and Dynamic Pyrolysis of EV Li-Ion Batteries2021In: Metals, ISSN 2075-4701, Vol. 11, no 8, article id 1240Article in journal (Refereed)
    Abstract [en]

    Selective leaching of Li from spent LIBs thermally pretreated by pyrolysis and incineration between 400 and 700 °C for 30, 60, and 90 min followed by water leaching at high temperature and high L/S ratio was examined. During the thermal pretreatment Li2CO3 and LiF were leached. Along with Li salts, AlF3 was also found to be leached with an efficiency not higher than 3.5%. The time of thermal pretreatment did not have a significant effect on Li leaching efficiency. The leaching efficiency of Li was higher with a higher L/S ratio. At a higher leaching temperature (80 °C), the leaching of Li was higher due to an increase in the solubility of present Li salts. The highest Li leaching efficiency of nearly 60% was observed from the sample pyrolyzed at 700 °C for 60 min under the leaching condition L/S ratio of 20:1 mL g−1 at 80 °C for 3 h. Furthermore, the use of an excess of 10% of carbon in a form of graphite during the thermal treatment did not improve the leaching efficiency of Li.

  • 12.
    Belonoshko, Anatoly
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory. Nanjing Univ, Frontiers Sci Ctr Crit Earth Mat Cycling, Sch Earth Sci & Engn, Nanjing 210023, Peoples R China; HSE Univ, Moscow Inst Elect & Math, Int Lab Supercomp Atomist Modelling & Multiscale A, Moscow 123458, Russia.; Univ S Florida, Dept Phys, Tampa, FL 33620 USA..
    Smirnov, Grigory S. S.
    HSE Univ, Moscow Inst Elect & Math, Int Lab Supercomp Atomist Modelling & Multiscale A, Moscow 123458, Russia.;Russian Acad Sci, Joint Inst High Temp, Moscow 125412, Russia..
    A Comparison of Experimental and Ab Initio Structural Data on Fe under Extreme Conditions2023In: Metals, ISSN 2075-4701, Vol. 13, no 6, article id 1096Article in journal (Refereed)
    Abstract [en]

    Iron is the major element of the Earth's core and the cores of Earth-like exoplanets. The crystal structure of iron, the major component of the Earth's solid inner core (IC), is unknown under the high pressures (P) (3.3-3.6 Mbar) and temperatures (T) (5000-7000 K) and conditions of the IC and exoplanetary cores. Experimental and theoretical data on the phase diagram of iron at these extreme PT conditions are contradictory. Though some of the large-scale ab initio molecular dynamics (AIMD) simulations point to the stability of the body-centered cubic (bcc) phase, the latest experimental data are often interpreted as evidence for the stability of the hexagonal close-packed (hcp) phase. Applying large-scale AIMD, we computed the properties of iron phases at the experimental pressures and temperatures reported in the experimental papers. The use of large-scale AIMD is critical since the use of small bcc computational cells (less than approximately 1000 atoms) leads to the collapse of the bcc structure. Large-scale AIMD allowed us to compare the measured and computed coordination numbers as well as the measured and computed structural factors. This comparison, in turn, allowed us to suggest that the computed density, coordination number, and structural factors of the bcc phase are in agreement with those observed in experiments, which were previously assigned either to the liquid or hcp phase.

  • 13.
    Bölke, Kristofer
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Andersson, Nils A. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Imris, Matej
    ScanArc Plasma Technol AB, SE-81321 Hofors, Sweden..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Experimental Determinations of Mixing Times in the IronArc Pilot Plant Process2019In: Metals, ISSN 2075-4701, Vol. 9, no 1, article id 101Article in journal (Refereed)
    Abstract [en]

    IronArc is a newly developed technology and an emerging future process for pig iron production. The long-term goal with this technology is to reduce the CO2 emissions and energy consumption compared to existing technologies. The production rate of this process is dependent on the stirring, which was investigated in the pilot plant process by measuring the mixing time in the slag bath. Moreover, slag investigations were done both based on light optical microscope studies as well as by Thermo-Calc calculations in order to determine the phases of the slag during operation. This was done because the viscosity (which is another important parameter) is dependent on the liquid and solid fractions of the slag. The overall results show that it was possible to determine the mixing time by means of the addition of a tracer (MnO2 powder) to the slag. The mixing time for the trials showed that the slag was homogenized after seconds. For two of the trials, homogenization had already been reached in the second sample after tracer addition, which means <= 8 s. The phase analysis from the slag indicated that the slag is in a liquid state during the operation of the process.

  • 14.
    Carlsson, Leo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Samuelsson, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Predicting the Electrical Energy Consumption of Electric Arc Furnaces Using Statistical Modeling2019In: Metals, ISSN 2075-4701, Vol. 9, no 9, article id 959Article, review/survey (Refereed)
    Abstract [en]

    Statistical modeling, also known as machine learning, has gained increased attention in part due to the Industry 4.0 development. However, a review of the statistical models within the scope of steel processes has not previously been conducted. This paper reviews available statistical models in the literature predicting the Electrical Energy (EE) consumption of the Electric Arc Furnace (EAF). The aim was to structure published data and to bring clarity to the subject in light of challenges and considerations that are imposed by statistical models. These include data complexity and data treatment, model validation and error reporting, choice of input variables, and model transparency with respect to process metallurgy. A majority of the models are never tested on future heats, which essentially renders the models useless in a practical industrial setting. In addition, nonlinear models outperform linear models but lack transparency with regards to which input variables are influencing the EE consumption prediction. Some input variables that heavily influence the EE consumption are rarely used in the models. The scrap composition and additive materials are two such examples. These observed shortcomings have to be correctly addressed in future research applying statistical modeling on steel processes. Lastly, the paper provides three key recommendations for future research applying statistical modeling on steel processes.

  • 15.
    Carlsson, Leo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Samuelsson, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Using statistical modeling to predict the electrical energy consumption of an electric arc furnace producing stainless steel2020In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 36Article in journal (Refereed)
    Abstract [en]

    The non-linearity of the Electric Arc Furnace (EAF) process and the correlative behavior between the process variables impose challenges that have to be considered if one aims to create a statistical model that is relevant and useful in practice. In this regard, both the statistical modeling framework and the statistical tools used in the modeling pipeline must be selected with the aim of handling these challenges. To achieve this, a non-linear statistical modeling framework known as Artificial Neural Networks (ANN) has been used to predict the Electrical Energy (EE) consumption of an EAF producing stainless steel. The statistical tools Feature Importance (FI), Distance Correlation (dCor) and Kolmogorov–Smirnov (KS) tests are applied to investigate the most influencing input variables as well as reasons behind model performance differences when predicting the EE consumption on future heats. The performance, measured as kWh per heat, of the best model was comparable to the performance of the best model reported in the literature while requiring substantially fewer input variables.

  • 16.
    Chanouian, Serg
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Larsson, Henrik
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    The Importance of Mixing Time in Intensely Stirred Metallurgical Reactors: Applied on Decarburization Reactions2023In: Metals, ISSN 2075-4701, Metals, E-ISSN 2075-4701, Vol. 13, no 10, article id 1694Article in journal (Refereed)
    Abstract [en]

    In metallurgical converter processes, numerical modeling is a useful tool for understanding the complexity of the systems. In this paper, we present a practical model that couples fluid dynamics and chemical reactions to explore the impact of mixing time on decarburization. Using computational fluid dynamics (CFD), in this study, we investigate an arbitrary metallurgical reactor with continuous oxygen supply, focusing on the Fe–C–O system. The model employs local equilibrium, a turbulence limiter, and finite volume method for mass, momentum, and energy transfer. Tracer injection points in the gas plume’s rising region exhibit faster mixing, and a comparison of reaction cases reveals distinct decarburization rates based on oxygen injection distribution and the influence of turbulence on reactions. Overall, while mixing time matters, the results show that this system is primarily governed by thermodynamics and oxygen supply, and a 270% increase in mixing time increase had a small impact on the end carbon content.

  • 17.
    Choi, Nuri
    et al.
    Hanyang Univ, Dept Mat Sci & Chem Engn, Ansan 15588, South Korea..
    Park, Nokeun
    Yeungnam Univ, Sch Mat Sci & Engn, Gyeongbuk 38541, South Korea..
    Kim, Jin-kyung
    Hanyang Univ, Dept Mat Sci & Chem Engn, Ansan 15588, South Korea..
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process. KTH Royal Inst Technol, Dept Mat Sci & Engn, S-10044 Stockholm, Sweden..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Park, Joo Hyun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Hanyang Univ, Dept Mat Sci & Chem Engn, Ansan 15588, South Korea..
    Influence of Manufacturing Conditions on Inclusion Characteristics and Mechanical Properties of FeCrNiMnCo Alloy2020In: Metals, ISSN 2075-4701, Vol. 10, no 10, article id 1286Article in journal (Refereed)
    Abstract [en]

    Three CoCrFeMnNi high-entropy alloys (HEAs) were produced by vacuum induction melting, induction melting under inert gas atmosphere, and melting under inert gas atmosphere followed by air exposure, respectively. The different manufacturing conditions for the three investigated alloys resulted in different levels and types of inclusions. The alloys melted under vacuum or inert gas contained Al2O3 inclusions formed by impurity Al, due to its high oxidation tendency. The molten alloy exposed in air showed an excessive oxidation. During oxidation of the molten alloy in air, impurity Al was initially oxidized, and fine MnCr2O4 inclusions were formed rather than pure Al2O3 inclusions. This difference was analyzed based on thermodynamic calculations. Specifically, the influence of impurity content on the inclusion characteristics was investigated for the three HEAs. Moreover, the inclusion characteristics were found to have an influence on mechanical properties of the alloys also. In air-exposed HEA, smaller inclusions were formed, resulting in a higher dislocation density at the matrix/inclusion interface and thus strengthening of the HEA. Thus, it is proposed that atmospheric conditions could be an important factor to control the inclusion characteristics and to form fine inclusion particles, which could improve the mechanical properties of HEAs.

  • 18.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Role of Glide during Creep of Copper at Low Temperatures2018In: Metals, ISSN 2075-4701, Vol. 8, no 10, article id 772Article in journal (Refereed)
    Abstract [en]

    Copper canister will be used in Scandinavia for final storage of spent nuclear fuel. The copper will be exposed to temperatures of up to 100 degrees C. The creep mechanism at near ambient temperatures has been assumed to be glide of dislocations, but this has never been verified for copper or other materials. In particular, no feasible mechanism for glide based static recovery has been proposed. To attack this classical problem, a glide mobility based on the assumption that it is controlled by the climb of the jogs on the dislocations is derived and shown that it is in agreement with observations. With dislocation dynamics (DD) simulations taking glide but not climb into account, it is demonstrated that creep based on glide alone can reach a quasi-stationary condition. This verifies that static recovery can occur just by glide. The DD simulations also show that the internal stress during creep in the loading direction is almost identical to the applied stress also directly after a load drop, which resolves further classical issues.

  • 19.
    Du, Hongying
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Björk, Thomas
    Ovako, Dept R&D, S-81382 Hofors, Sweden.;Ovako, Dept R&D, S-81382 Hofors, Sweden..
    Löyquist, Simon
    AB Sandvik Coromant, Dept R&D Verificat Component & Mat, Mossvagen 10, S-81181 Sandviken, Sweden.;AB Sandvik Coromant, Dept R&D Verificat Component & Mat, Mossvagen 10, S-81181 Sandviken, Sweden..
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Assessment of Chip Breakability during Turning of Stainless Steels Based on Weight Distributions of Chips2020In: Metals, ISSN 2075-4701, Vol. 10, no 5, article id 675Article in journal (Refereed)
    Abstract [en]

    Currently, the available evaluation methods for determining the chip breakability in the industry are mainly based on subjective visual assessment of the chip formation by an operator during machining or on chips that were collected after the tests. However, in many cases, these methods cannot give us accurate quantitative differences for evaluation of the chip breakability of similar steel grades and similar sets of machining parameters. Thus, more sensitive methods are required to obtain more detailed information. In this study, a new method for the objective assessment of chip breakability based on quantitative determination of the weight distribution of chips (WDC) was tested and applied during machining of stainless steels without Ca treatment (316L) and with Ca treatment (316L + Ca). The obtained results show great consistencies and the reliability of this method. By using the WDC method, significant quantitative differences were obtained by the evaluation of chips, which were collected during the machining process of these two similar grades of steel at various cutting parameters, while, visually, these chips look very similar. More specifically, it was found that the Ca treatment of steel can improve the chip breakability of 316L + Ca steel in 80% of cutting trials, since a fraction of small light chips (Type I) from this steel increased and a fraction of large heavy chips (Type III) decreased accordingly. Moreover, the WDCs that were obtained at different cutting parameters were determined and compared in this study. The obtained results can be used for the optimization of chip breakability of each steel at different cutting parameters. The positive effect of Ca treatment of stainless steel was discussed in this study based on consideration of the modification of different non-metallic inclusions and their effect on the chip breakability during machining.

  • 20.
    Du, Hongying
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Sundqvist, Olle
    Sandv Mat Technol AB, S-81181 Sandviken, Sweden..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Modification of Non-Metallic Inclusions in Stainless Steel by Addition of CaSi2019In: Metals, ISSN 2075-4701, Vol. 9, no 1, article id 74Article in journal (Refereed)
    Abstract [en]

    The focus of this study involved comparative investigations of non-metallic inclusions in 316L stainless steel bars without and with Ca treatments. The inclusions were extracted by using electrolytic extraction (EE). After that, the characteristics of the inclusions, such as morphology, size, number, and composition, were investigated by using a scanning electron microscope (SEM) in combination with an energy dispersive X-ray spectroscopy (EDS). The following four types of inclusions were observed in 316L steels: (1) Elongated MnS (Type I), (2) MnS with hard oxide cores (Type II), (3) Undeformed irregular oxides (Type III), and (4) Elongated oxides with a hard oxide core (Type IV). In the reference sample, only a small amount of the Type III oxides (Al2O3-MgO-MnO-TiOx) existed. However, in Ca-treated 316L steel, about 46% of the observed inclusions were oxide inclusions (Types III and IV) correlated to gehlenite and to a mixture of gehlenite and anorthite, which are favorable for the machinability of steel. Furthermore, untransformed oxide cores (Al2O3-MgO-MnO) were also found in the inclusions of Type IV. The mechanism leading to different morphologies of oxide inclusions is also discussed.

  • 21.
    Enoki, Masanori
    et al.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat IMRAM, Sendai, Miyagi 9808577, Japan..
    Sundman, Bo
    OpenCalphad, 9 Allee Acerma, F-91190 Gif Sur Yvette, France..
    Sluiter, Marcel H. F.
    Delft Univ Technol, Mat Sci & Engn, NL-2600 AA Delft, Netherlands..
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohtani, Hiroshi
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat IMRAM, Sendai, Miyagi 9808577, Japan..
    Calphad Modeling of LRO and SRO Usingab initioData2020In: Metals, ISSN 2075-4701, Vol. 10, no 8, article id 998Article, review/survey (Refereed)
    Abstract [en]

    Results from DFT calculations are in many cases equivalent to experimental data. They describe a set of properties of a phase at a well-defined composition and temperature,T, most often at 0 K. In order to be practically useful in materials design, such data must be fitted to a thermodynamic model for the phase to allow interpolations and extrapolations. The intention of this paper is to give a summary of the state of the art by using the Calphad technique to model thermodynamic properties and calculate phase diagrams, including some models that should be avoided. Calphad models can decribe long range ordering (LRO) using sublattices and there are model parameters that can approximate short range ordering (SRO) within the experimental uncertainty. In addition to the DFT data, there is a need for experimental data, in particular, for the phase diagram, to determine the model parameters. Very small differences in Gibbs energy of the phases, far smaller than the uncertainties in the DFT calculations, determine the set of stable phases at varying composition andT. Thus, adjustment of the DFT results is often needed in order to obtain the correct set of stable phases.

  • 22.
    Frisk, Robin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Andersson, Nils A. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Rogberg, Bo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy2019In: Metals, ISSN 2075-4701, Vol. 9, no 6Article in journal (Refereed)
    Abstract [en]

    The structure and segregation of a continuously cast iron-nickel based superalloy were investigated. Cross-sectional samples were prepared from the central section of a 150 x 150 mm square billet. The microporosity was measured from the surface to the center and theoretical conditions for pore formation were investigated. A central porosity, up to 10 mm in width, was present in the center of the billet. The measured secondary arm spacing was correlated with a calculated cooling rate and a mathematical model was obtained. Spinel particles were found in the structure, which acted as inoculation points for primary austenite and promoted the formation of the central equiaxed zone. Titanium segregated severely in the interdendritic areas and an increase of Ti most likely lead to a significant decrease in the hot ductility. Precipitates were detected in an area fraction of approximately 0.55% across the billet, which were identified as Ti(CN), TiN, eta -Ni3Ti, and a phosphide phase.

  • 23.
    Guo, Shuo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Evaluation of Sulfide Inclusions before and after Deformation of Steel by Using the Electrolytic Extraction Method2021In: Metals, ISSN 2075-4701, Vol. 11, no 4, article id 543Article in journal (Refereed)
    Abstract [en]

    The characteristics of elongated MnS have a critical effect on fatigue anisotropy and all mechanical anisotropies. A comparative investigation of nonmetallic inclusions in both stainless steels and tool steels has been carried out in this study. The inclusion characteristics were investigated using electrolytic extraction (EE) followed by scanning electron microscopy combined with energy-dispersive spectroscopy (SEM-EDS). Overall, three types of MnS inclusions (type I (regular), type II (irregular) and type III (Rod)) were found in tool steels in as-cast samples, which had not been heat-treated. Furthermore, three types of MnS inclusions (Rod-like sulfide (RS), Plate-like sulfide (PS) and Oxysulfide (OS)) were found in samples taken after rolling. Based on the breakability of the elongated MnS, three types of inclusions, Type UU, UB and BB, where U represents the undamaged or unbroken edge of an inclusion and B represents the fragment or broken edge of an inclusion, were studied in both stainless steels and tool steels both before and after additional heat treatment. The effect of heat treatment and dissolving the metal layer during the EE process is also discussed. The results show that both processes have a limited effect on the breakability of inclusions in steels with carbon contents <0.42 mass%.

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  • 24.
    Hao, Xiaole
    et al.
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, 52 Xuefu Rd, Harbin 150080, Peoples R China..
    Yue, Caixu
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, 52 Xuefu Rd, Harbin 150080, Peoples R China..
    Liu, Xianli
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, 52 Xuefu Rd, Harbin 150080, Peoples R China..
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Liang, Steven Y.
    Georgia Inst Technol, Woodruff Sch Mech Engn, Atlanta, GA 30332 USA..
    Nan, Yuechong
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, 52 Xuefu Rd, Harbin 150080, Peoples R China..
    Modeling of Convex Surface Topography in Milling Process2020In: Metals, ISSN 2075-4701, Vol. 10, no 9, article id 1218Article in journal (Refereed)
    Abstract [en]

    Cr12MoV die steel is a typical high-strength and high-hardness material. Because of the high hardness of Cr12MoV die steel, which is approximately 50-65 HRC after quenching, and the tool's weak rigidity, cutting vibration, and tool deformation are inevitable during the cutting process. In this paper, a model for predicting the surface topography of a convex curved die steel machined by a ball-end milling cutter was established. In addition, the surface springback of the workpiece is considered. According to the surface characteristics of the convex curved workpiece, the vector algorithm and transformation matrix are applied to calculate the milling cutter motion trajectory equation. Then, the influence of dynamic factors on the tool path is calculated, and finally the surface topography of the workpiece is simulated through the Z-map model. The simulation error of three-dimensional surface roughnessSaat different positions of the curved surface is between 10% and 16%. After considering the dynamic factors, the simulation error is reduced by about 50%.

  • 25.
    Huitron, Rosa Maria Pineda
    et al.
    Luleå Univ Technol, Dept Engn Sci & Math, Mat Sci, SE-97187 Luleå, Sweden..
    Lopez, Pavel Ernesto Ramirez
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. SWERIM AB, Proc Met Dept, Casting & Flow Simulat Grp, Aronstorpsvagen 1, SE-97437 Luleå, Sweden..
    Vuorinen, Esa
    Luleå Univ Technol, Dept Engn Sci & Math, Mat Sci, SE-97187 Luleå, Sweden..
    Jalali, Pooria Nazen
    SWERIM AB, Proc Met Dept, Casting & Flow Simulat Grp, Aronstorpsvagen 1, SE-97437 Luleå, Sweden..
    Pelcastre, Leonardo
    Luleå Univ Technol, Dept Engn Sci & Math, Mat Sci, SE-97187 Luleå, Sweden..
    Karkkainen, Maija
    SSAB Europe Oy Raahe Works, Rautaruukintie 155,PL 93, Raahe 92101, Finland..
    Scale Formation on HSLA Steel during Continuous Casting Part I: The Effect of Temperature-Time on Oxidation Kinetics2020In: Metals, ISSN 2075-4701, Vol. 10, no 9, article id 1243Article in journal (Refereed)
    Abstract [en]

    The findings in this work enhance the understanding of oxidation mechanisms and scale growth at high temperatures of a high strength low alloy (HSLA) steel for improving surface quality during continuous casting. The oxidation phenomenon was investigated under dry air and water vapor atmospheres by heating specimens at 1000, 1100, and 1200 degrees C at different holding times. Temperature and time had great effects on the kinetics, where faster (i.e., parabolic) oxidation rates were present under water vapor when compared with the dry air condition. Temperature strongly influenced the number of defects, such as pores, voids, gaps and micro-cracks, formed in the oxide scale. A phase analysis confirmed the presence of FeO as the first phase formed at the steel surface, Fe(3)O(4)as the middle and thicker phase, and Fe(2)O(3)as the last phase formed in the oxide/air interface. The micromechanics of the oxides demonstrated that a combination of phases with high (wustite) and low plasticity (magnetite and hematite) could also have been the reason for the uneven cooling during Continuous Casting (CC) that resulted in the undesired surface quality of the steel slabs. This work gives a good look at the oxide scale effect on the surface quality of steel slabs through an understanding the kinetics during oxidation.

  • 26.
    Huitron, Rosa Maria Pineda
    et al.
    Luleå Univ Technol, Dept Engn Sci & Math, Mat Sci, SE-97187 Luleå, Sweden..
    Lopez, Pavel Ernesto Ramirez
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. SWERIM AB, Proc Met Dept, Casting & Flow Simulat Grp, Aronstorpsvagen 1, SE-97437 Luleå.
    Vuorinen, Esa
    Luleå Univ Technol, Dept Engn Sci & Math, Mat Sci, SE-97187 Luleå, Sweden..
    Jalali, Pooria Nazen
    SWERIM AB, Proc Met Dept, Casting & Flow Simulat Grp, Aronstorpsvagen 1, SE-97437 Luleå, Sweden..
    Pelcastre, Leonardo
    Luleå Univ Technol, Dept Engn Sci & Math, Mat Sci, SE-97187 Luleå, Sweden..
    Karkkainen, Maija
    SSAB Europe Oy Raahe Works, Rautaruukintie 155,PL 93, Raahe 92101, Finland..
    Scale Formation on HSLA Steel during Continuous Casting Part II: The Effect of Surface Conditions2020In: Metals, ISSN 2075-4701, Vol. 10, no 9, article id 1245Article in journal (Refereed)
    Abstract [en]

    The present research addresses the effect of surface condition on oxide scale formation at high temperatures such as those experienced during secondary cooling in Continuous Casting. Tests were carried out in clean, as-cast and surfaces covered with casting powder to replicate the oxidation/re-oxidation after the mould. Specimens oxidized at 1000, 1100 and 1200 degrees C under dry air and water-vapour conditions revealed that the oxide scale formation is strongly influenced by temperature, environmental and surface conditions. The oxide scale thickness increases with temperature alterations in the surface (e.g., as-cast and covered with powder) where oxides and carbonates from the casting powder accelerate oxidation kinetics leading to thick and unstable scales. A high amount of carbon is present on surfaces covered with casting powder where it diffuses through the oxide scale forming CO and CO2 which lead to stress accumulation that makes scales prone to defects such as pores, voids and micro-cracks. Ultimately, if wustite remains attached to the steel surface or inside oscillation marks, it may disturb heat transfer during secondary cooling which has deep industrial implications for crack formation and overall casting yield. Therefore, accurate insights on scale type and growth mechanisms could lead to accurate control of its formation during casting.

  • 27.
    Hultgren, Gustav
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Myrén, Leo
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Mansour, Rami
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Digital scanning of welds and influence of sampling resolution on the predicted fatigue performance: modelling, experiment and simulation2021In: Metals, ISSN 2075-4701, Vol. 11, no 5, article id 822Article in journal (Refereed)
    Abstract [en]

    Digital weld quality assurance systems are increasingly used to capture local geometrical variations that can be detrimental for the fatigue strength of welded components. In this study, a method is proposed to determine the required scanning sampling resolution for proper fatigue assessment. Based on FE analysis of laser‐scanned welded joints, fatigue failure probabilities are computed using a Weakest‐link fatigue model with experimentally determined parameters. By down‐sampling of the scanning data in the FE simulations, it is shown that the uncertainty and error in the fatigue failure probability prediction increases with decreased sampling resolution. The required sampling resolution is thereafter determined by setting an allowable error in the predicted failure probability. A sampling resolution of 200 to 250 μm has been shown to be adequate for the fatigue‐loaded welded joints investigated in the current study. The resolution requirements can be directly incorporated in production for continuous quality assurance of welded structures. The proposed probabilistic model used to derive the resolution requirement accurately captures the experimental fatigue strength distribution, with a correlation coefficient of 0.9 between model and experimental failure probabilities. This work therefore brings novelty by deriving sampling resolution requirements based on the influence of stochastic topographical variations on the fatigue strength distribution. 

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  • 28.
    Ibrahim, Mohammad
    et al.
    Department of Engineering Sciences, University of Agder (UiA), Grimstad, 4879, Norway.
    Du, Qiang
    SINTEF Industry, Department of Metal Production and Processing, Oslo, 0314, Norway.
    Hovig, Even Wilberg
    SINTEF Industry, Department of Metal Production and Processing, Oslo, 0314, Norway.
    Grasmo, Geir
    Department of Engineering Sciences, University of Agder (UiA), Grimstad, 4879, Norway.
    Hulme-Smith, Christopher
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Aune, Ragnhild E.
    Department of Engineering Sciences, University of Agder (UiA), Grimstad, 4879, Norway; Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, 7491, Norway.
    Gas-Atomized Nickel Silicide Powders Alloyed with Molybdenum, Cobalt, Titanium, Boron, and Vanadium for Additive Manufacturing2023In: Metals, ISSN 2075-4701, Vol. 13, no 9, article id 1591Article in journal (Refereed)
    Abstract [en]

    Nickel silicides (NiSi) are renowned for their ability to withstand high temperatures and resist oxidation and corrosion in challenging environments. As a result, these alloys have garnered interest for potential applications in turbine blades and underwater settings. However, their high brittleness is a constant obstacle that hinders their use in producing larger parts. A literature review has revealed that incorporating trace amounts of transition metals can enhance the ductility of silicides. Consequently, the present study aims to create NiSi-based powders with the addition of titanium (Ti), boron (B), cobalt (Co), molybdenum (Mo), and vanadium (V) for Additive Manufacturing (AM) through the process of gas atomization. The study comprehensively assesses the microstructure, phase composition, thermal properties, and surface morphology of the produced powder particles, specifically NiSi11.9Co3.4, NiSi10.15V4.85, NiSi11.2Mo1.8, and Ni-Si10.78Ti1.84B0.1. Commonly used analytical techniques (SEM, EDS, XRD, DSC, and laser diffraction) are used to identify the alloy configuration that offers optimal characteristics for AM applications. The results show spherical particles within the size range of 20–63 μm, and only isolated satellites were observed to exist in the produced powders, securing their smooth flow during AM processing.

  • 29. Jarfors, Anders E. W.
    et al.
    Zhang, Qing
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Feeding and Pore Formation in Semisolid Metal Casting2020In: Metals, ISSN 2075-4701, Vol. 10, no 11, article id 1560Article in journal (Refereed)
    Abstract [en]

    Semisolid casting can provide excellent castings, but the nature of the pore-forming mechanisms has not been properly clarified. In the current communication, it was suggested that hydrogen precipitated during slurry making might have a decisive role in the formation of both gas and shrinkage porosity. Intensive stirring at the end of the slurry making process may act as a degassing step. Without the intense shearing, structures of primary slurry particles form around the hydrogen pores, strongly affecting pore formation and feeding during the intensification stage.

  • 30.
    Karasev, Andrey
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Gorkusha, Dmitry
    RAS, Baikov Inst Met & Mat Sci, Moscow 119911, Russia..
    Grigorovich, Konstantin, V
    RAS, Baikov Inst Met & Mat Sci, Moscow 119911, Russia.;Natl Univ Sci & Technol MISIS MISIS, Met Steel & Ferroalloys, Moscow 119049, Russia..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Application of Some Modern Analytical Techniques for Characterization of Non-Metallic Inclusions in a Fe-10mass%Ni Alloy Deoxidized by Ti/Zr and Ti/Mg2021In: Metals, ISSN 2075-4701, Vol. 11, no 3, article id 448Article in journal (Refereed)
    Abstract [en]

    In this study, a complete and comprehensive analysis of non-metallic inclusions (NMI) in an Fe-10%Ni alloy was done by using two modern analytical methods that complement each other: Electrolytic Extraction (EE) of inclusions from metal samples followed by investigations by using Scanning Electron Microscopy (SEM) and Fractional Gas Analysis (FGA). The composition, morphology, size and number of different NMIs and clusters were investigated in metal samples taken after deoxidation by additions of Ti, Ti/Zr and Ti/Mg. The obtained results were discussed with respect to formation, modification and removal of NMIs and clusters depending on the type of deoxidations and the holding time. It was found that the peaks of oxygen reduced from different oxide inclusions obtained by the FGA measurements corresponded well to the main types of inclusions and clusters observed by using the EE + SEM method. More specifically, the total O content in oxide inclusions (O-NMI) increases by 10% after a Zr addition and then decreases linearly by 40% during 5 min of holding due to flotation of NMIs and clusters. However, after a Mg addition in the melt deoxidized by Ti, the O-NMI content decreases drastically by 63% during 5 min of holding, due to a fast floatation of NMIs caused by bubbles of vaporized Mg.

  • 31.
    Karlsson Hagnell, Mathilda
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Khurshid, Mansoor
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures. Cargotec Sweden AB Bromma Conquip, Kronborgsgrand 23,Box 1133, S-16422 Kista, Sweden.
    Åkermo, Malin
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures.
    Design Implications and Opportunities of Considering Fatigue Strength, Manufacturing Variations and Predictive LCC in Welds2021In: Metals, ISSN 2075-4701, Vol. 11, no 10, article id 1527Article in journal (Refereed)
    Abstract [en]

    Fatigue strength dictates life and cost of welded structures and is often a direct result of initial manufacturing variations and defects. This paper addresses this coupling through proposing and applying the methodology of predictive life-cycle costing (PLCC) to evaluate a welded structure exhibiting manufacturing-induced variations in penetration depth. It is found that if a full-width crack is a fact, a 50% thicker design can result in life-cycle cost reductions of 60% due to reduced repair costs. The paper demonstrates the importance of incorporating manufacturing variations in an early design stage to ensure an overall minimized life-cycle cost.

  • 32.
    Kaya, Şerif
    et al.
    Middle East Technical University.
    Peters, Edward Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Dittrich, Carsten
    MEAB Chemie Technik GmbH.
    Stopic, Srecko
    RWTH Aachen University.
    Friedrich, Bernd
    RWTH Aachen University.
    Scandium Recovery from an Ammonium Fluoride Strip Liquor by Anti-Solvent Crystallization2018In: Metals, ISSN 2075-4701, Vol. 8, no 10Article in journal (Refereed)
    Abstract [en]

    In this study, the crystallization of scandium from ammonium fluoride strip liquor, obtained by solvent extraction, was investigated using an anti-solvent crystallization technique. Acetone, ethanol, methanol and isopropanol were added individually to the strip liquor as the anti-solvent and scandium was precipitated and obtained in the form of (NH4)3ScF6 crystals. The results show that scandium can be effectively crystallized from the strip liquor to obtain an intermediate, marketable scandium product. Yields greater than 98% were obtained using an anti-solvent to strip liquor volumetric ratio of 0.8. Acetone had the least performance at lower anti-solvent to strip liquor volumetric ratios, possibly due to its limited H bonding capability with water molecules when compared to alcohols.

  • 33.
    Khan, Fareed
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Effect of Soaking on Segregation and Primary-Carbide Dissolution in Ingot-Cast Bearing Steel2018In: Metals, ISSN 2075-4701, Vol. 8, no 10, article id 800Article in journal (Refereed)
    Abstract [en]

    In this work, segregation in the cast and hot worked structure, as well as the effects of soaking on macro and micro segregation, in hypereutectoid bearing steel produced by ingot casting were studied. Samples were selected from ingots that where either as cast or soaked for twenty hours. Two similar bearing steel grades were used for this investigation. For the as cast ingot, samples were selected from both A-segregation channel regions and the matrix region. Samples were also selected from hot-worked bars originating from ingots that had been soaked for four hours or twenty hours. Micro and macro examinations of the microstructures were conducted and compared. In addition, a segregation analysis of the substitutional solute elements was performed using EDX equipment mounted on a Scanning Electron Microscope (SEM). EMPA mapping of the composition pattern in the bulk, as well as the carbides, was conducted. Precipitation of M3C, M2C, and M6C was observed. The carbides at A-segregation channels were found to have a different morphology to those precipitated in the bulk matrix. After soaking at 1200 degrees C for 4 h, all the primary carbides are dissolved.

  • 34.
    Kohlstädt, Sebastian
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process. Volkswagen AG, Div Components Mfg, Dr Rudolf Leiding Pl 1, D-34225 Baunatal, Germany..
    Vynnycky, Michael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process. Univ Limerick, Dept Math & Stat, Limerick V94 T9PX, Ireland..
    Goeke, Stephan
    Kassel Univ, Inst Mech, Monchebergstr 7, D-34125 Kassel, Germany..
    On the CFD Modelling of Slamming of the Metal Melt in High-Pressure Die Casting Involving Lost Cores2021In: Metals, ISSN 2075-4701, Vol. 11, no 1, article id 78Article in journal (Refereed)
    Abstract [en]

    This paper uses computational fluid dynamics (CFD), in the form of the OpenFOAM software package, to investigate the forces on the salt core in high-pressure die casting (HPDC) when being exposed to the impact of the inflowing melt in the die filling stage, with particular respect to the moment of first impact-commonly known as slamming. The melt-air system is modelled via an Eulerian volume-of-fluid approach, treating the air as a compressible perfect gas. The turbulence is treated via a Reynolds-averaged Navier Stokes (RANS) approach. The RNG k-epsilon and the Menter SST k-omega models are both evaluated, with the use of the latter ultimately being adopted for batch computations. A study of the effect of the Courant number, with a view to establishing mesh independence, indicates that meshes which are finer, and time steps that are smaller, than those previously employed for HPDC simulations are required to capture the effect of slamming on the core properly, with respect to existing analytical models and empirical measurements. As a second step, it is then discussed what response should be expected when this force, with its spike-like morphology and small force-time integral, impacts the core. It is found that the displacement of the core due to the spike in the force is so small that, even though the force is high in value, the bending stress inside the core remains below the critical limit for fracture. It can therefore be concluded that, when assuming homogeneous crack-free material conditions, the spike in the force is not failure-critical.

  • 35.
    Korkmaz, Kivanc
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmood
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Sustainable Hydrometallurgical Recovery of Valuable Elements from Spent Nickel-Metal Hydride HEV Batteries2018In: Metals, ISSN 2075-4701, Vol. 8, no 12, p. 1062-Article in journal (Refereed)
    Abstract [en]

    In the present study, the recovery of valuable metals from a Panasonic Prismatic Module 6.5 Ah NiMH 7.2 V plastic casing hybrid electric vehicle (HEV) battery has been investigated, processing the anode and cathode electrodes separately. The study focuses on the recovery of the most valuable compounds, i.e., nickel, cobalt and rare earth elements (REE). Most of the REE (La, Ce, Nd, Pr and Y) were found in the anode active material (33% by mass), whereas only a small amount of Y was found in the cathode material. The electrodes were leached in sulfuric acid and in hydrochloric acid, respectively, under different conditions. The results indicated that the dissolution kinetics of nickel could be slow as a result of slow dissolution kinetics of nickel oxide. At leaching in sulfuric acid, light rare earths were found to reprecipitate increasingly with increasing temperature and sulfuric acid concentration. Following the leaching, the separation of REE from the sulfuric acid leach liquor by precipitation as NaREE (SO4)(2)center dot H2O and from the hydrochloric acid leach solution as REE2 (C2O4)(3)center dot xH(2)O were investigated. By adding sodium ions, the REE could be precipitated as NaREE (SO4)2 center dot H2O with little loss of Co and Ni. By using a stoichiometric oxalic acid excess of 300%, the REE could be precipitated as oxalates while avoiding nickel and cobalt co-precipitation. By using nanofiltration it was possible to recover hydrochloric acid after leaching the anode material.

  • 36.
    Korzhavyi, Pavel A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Zhang, Jing
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Free energy of metals from quasi-harmonic models of thermal disorder2021In: Metals, ISSN 2075-4701, Vol. 11, no 2, p. 195-Article in journal (Refereed)
    Abstract [en]

    A simple modelling method to extend first-principles electronic structure calculations to finite temperatures is presented. The method is applicable to crystalline solids exhibiting complex thermal disorder and employs quasi-harmonic models to represent the vibrational and magnetic free energy contributions. The main outcome is the Helmholtz free energy, calculated as a function of volume and temperature, from which the other related thermophysical properties (such as temperature-dependent lattice and elastic constants) can be derived. Our test calculations for Fe, Ni, Ti, and W metals in the paramagnetic state at temperatures of up to 1600 K show that the predictive capability of the quasi-harmonic modelling approach is mainly limited by the electron density functional approximation used and, in the second place, by the neglect of higher-order anharmonic effects. The developed methodology is equally applicable to disordered alloys and ordered compounds and can therefore be useful in modelling realistically complex materials.

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  • 37.
    Kuznetsov, Andrey
    et al.
    RAS, Ural Branch, Inst Met Phys, Ekaterinburg 620108, Russia..
    Karkina, Lidia
    RAS, Ural Branch, Inst Met Phys, Ekaterinburg 620108, Russia..
    Gornostyrev, Yuri
    RAS, Ural Branch, Inst Met Phys, Ekaterinburg 620108, Russia..
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Effects of Zn and Mg Segregations on the Grain Boundary Sliding and Cohesion in Al: Ab Initio Modeling2021In: Metals, ISSN 2075-4701, Vol. 11, no 4, article id 631Article in journal (Refereed)
    Abstract [en]

    The formation of Zn and Mg segregations at a tilt sigma 5{013} grain boundary (GB) in Al and the effects of these solutes on deformation behavior of polycrystalline Al were investigated using ab initio total energy calculations. Using a step-by-step modeling of the segregation process, we found that the formation of a thick segregation layer of Zn at the GB is energetically preferable, while the formation of an atomically thin segregation layer is expected in the case of Mg. To reveal the effect of segregation on the cohesive properties of Al GBs, we calculated the energy of cleavage decohesion and the shear resistance for GB sliding. We show that the segregation of Zn results in a substantial decrease in barriers for GB sliding, while the segregation of Mg increases the barriers. The results obtained allow us to explain experimental findings and demonstrate a strong relationship between chemical bonding of solute atoms, their segregation ability, and GB strength.

  • 38.
    Liu, Jianling
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Das, Yadunandan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures. Open Univ, Mat Engn, Walton Hall, Milton Keynes MK7 6AA, Bucks, England..
    King, Stephen M.
    STFC Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Source, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Jonsson, Jan Y.
    Outokumpu Stainless AB, R&D Avesta, POB 74, SE-77422 Avesta, Sweden..
    Wessman, Sten
    Swerim AB, POB 7047, SE-16407 Kista, Sweden..
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Effect of Cooling Rate after Solution Treatment on Subsequent Phase Separation Evolution in Super Duplex Stainless Steel 25Cr-7Ni (wt.%)2022In: Metals, ISSN 2075-4701, Vol. 12, no 5, p. 890-, article id 890Article in journal (Refereed)
    Abstract [en]

    The effect of cooling rate after solution treatment on the initial structure of super duplex stainless steel 25Cr-7Ni (wt.%), and the effect of the initial structure on phase separation (PS) evolution during subsequent aging were investigated. The nanostructure in the bulk of the steel was studied using small-angle neutron scattering (SANS). Ex situ SANS experiments showed that the rate of PS differs during aging, due to the different initial structures imposed by the difference in cooling rate after solution treatment. In situ SANS experiments revealed that the PS is already pronounced after aging at 475 degrees C for 180 min and that a slower cooling rate after solution treatment will lead to more significant PS. Hence, PS depends on the plate thickness, imposing different cooling rates in the production of duplex stainless steels.

  • 39.
    Liu, Yu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. KTH-Royal Institute of Technology.
    Bai, Haitong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Liu, Heping
    Cent Iron & Steel Res Inst, 76 Xueyuan Nanlu, Beijing 100081, Peoples R China..
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing. KTH-Royal Institute of Technology.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing. KTH-Royal Institute of Technology.
    Gan, Yong
    Cent Iron & Steel Res Inst, 76 Xueyuan Nanlu, Beijing 100081, Peoples R China..
    Physical and Numerical Modelling on the Mixing Condition in a 50 t Ladle2019In: Metals, ISSN 2075-4701, Vol. 9, no 11, article id 1136Article in journal (Refereed)
    Abstract [en]

    The bubbly flow and mixing conditions for gas stirring in a 50t ladle were investigated by using physical modelling and mathematical modelling. In the physical modelling, the effect of the porous plugs' configurations on the tracer homogenization was studied by using a saturated NaCl solution to predict the mixing time and a color dye to show the mixing pattern. In the mathematical modelling, the Euler-Lagrange model and species transport model were used to predict the flow pattern and tracer homogenization, respectively. The results show that, for a +/- 5% homogenization degree, the mixing time with dual plugs using a radial angle of 180 degrees is shortest. In addition, the mixing time using a radial angle of 135 degrees decreases the most with an increased flow rate. The flow pattern and mixing conditions predicted by mathematical modelling agree well with the result of the physical modelling. For a +/- 1% homogenization degree, the influence of the tracer's natural convection on its homogenization pattern cannot be neglected. This is especially true for a 'soft bubbling' case using a low gas flow rate. Overall, it is recommended that large radial angles in the range of 135 degrees 180 degrees are chosen for gas stirring in the present study when using dual porous plugs.

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  • 40.
    Lousada, Claudio M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Segregation of P and S Impurities to A Sigma 9 Grain Boundary in Cu2020In: Metals, ISSN 2075-4701, Vol. 10, no 10, article id 1362Article in journal (Refereed)
    Abstract [en]

    The segregation of P and S to grain boundaries (GBs) in fcc Cu has implications in diverse physical-chemical properties of the material and this can be of particular high relevance when the material is employed in high performance applications. Here, we studied the segregation of P and S to the symmetric tilt Sigma 9 (22 over bar 1 over bar ) [110], 38.9 degrees GB of fcc Cu. This GB is characterized by a variety of segregation sites within and near the GB plane, with considerable differences in both atomic site volume and coordination number and geometry. We found that the segregation energies of P and S vary considerably both with distance from the GB plane and sites within the GB plane. The segregation energy is significantly large at the GB plane but drops to almost zero at a distance of only approximate to 3.5 angstrom from this. Additionally, for each impurity there are considerable variations in energy (up to 0.6 eV) between segregation sites in the GB plane. These variations have origins both in differences in coordination number and atomic site volume with the effect of coordination number dominating. For sites with the same coordination number, up to a certain atomic site volume, a larger atomic site volume leads to a stronger segregation. After that limit in volume has been reached, a larger volume leads to weaker segregation. The fact that the segregation energy varies with such magnitude within the Sigma 9 GB plane may have implications in the accumulation of these impurities at these GBs in the material. Because of this, atomic-scale variations of concentration of P and S are expected to occur at the Sigma 9 GB center and in other GBs with similar features.

  • 41.
    Lundkvist, Axel
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Barsoum, Imad
    Khalifa Univ Sci & Technol, Dept Mech Engn, Abu Dhabi, U Arab Emirates.;Khalifa Univ Sci & Technol, Adv Digital & Addit Mfg Ctr, Abu Dhabi, U Arab Emirates..
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Khurshid, Mansoor
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. Cargotec Sweden AB Bromma Conquip, Kronborgsgrand 23, S-16446 Kista, Sweden..
    Geometric and Material Modelling Aspects for Strength Prediction of Riveted Joints2023In: Metals, ISSN 2075-4701, Vol. 13, no 3, p. 500-, article id 500Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to develop a methodology for static strength and failure mode simulation of hot-driven riveted joints. The purpose is to be able to accurately estimate a rivet joint's static strength behaviour and its failure mode without relying on experiments, to save both time and resources during the design of joints. The non-linear finite element analysis modelling framework considered the rivet joint configurations and geometry, the material properties of the plate and rivet as well as the clamping force of the hot-driven rivet. A ductile damage model was also implemented to capture the stress softening of the materials and the failure modes of the joints. Using experimental data from literature, the modelling framework is validated, and it is shown that it is able to capture the strength behaviour and failure modes of different configurations of rivet joints markedly well. The effect of the rivet pre-load on the mechanical response of the joint is also studied and it is shown that the strength of the joint increased with the increase in rivet pre-load. The modelling framework is then applied to an industrial component. The modelling framework is used to compare welding and riveting as joining methods in a component built in two grades of high-strength steel. It is found that the welded joint possessed greater strength compared to the proposed riveted joint. However, using the proposed simulation methodology developed, a riveted joint with matching strength to the welded joint could be designed.

  • 42.
    Lyu, Yezhe
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Department of Mechanical Engineering Sciences, Lund University, Lund, SE-22100, Sweden.
    Leonardi, M.
    Mancini, A.
    Wahlström, Jens
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Tribology and airborne particle emission of laser-cladded fe-based coatings versus non-asbestos organic and low-metallic brake materials2021In: Metals, ISSN 2075-4701, Vol. 11, no 11, article id 1703Article in journal (Refereed)
    Abstract [en]

    Laser cladding is a promising surface treatment for refurbishing worn-out cast-iron brake rotors. Previous studies on laser-cladded brake rotors have demonstrated their extensively higher wear and greater airborne particle emissions, compared with traditional cast iron rotors. In order to overcome this, a commercial non-asbestos organic (NAO) brake material is tested against Fe-based laser-cladded and traditional cast-iron brake rotors. Two low-metallic brake pad materials are also tested as references. The materials’ coefficients of friction, specific wear rates and particle number concentrations are evaluated. The results indicate that the NAO brake material showed lower wear and had fewer particle emissions than the low-metallic brake materials when deployed against both cast iron and laser-cladded brake rotors. The NAO/laser-cladding friction pairing showed wear, particle concentration and fraction of fine particles (sub 1 µm) equivalent to those of the low-metallic/cast-iron friction pairing, creating significant potential for application in refurbishing worn-out cast-iron brake rotors.

  • 43.
    Ma, Yiqian
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery. RWTH Aachen University.
    Stopic, Srecko
    RWTH Aachen University.
    Wang, Xuewen
    Central South University.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Friedrich, Bernd
    RWTH Aachen University.
    Basic Sulfate Precipitation of Zirconium from Sulfuric Acid Leach Solution2020In: Metals, ISSN 2075-4701, Vol. 10, no 8, p. 1099-Article in journal (Refereed)
    Abstract [en]

    H2SO4 was ensured to be the best candidate for Zr leaching from the eudialyte. The resulting sulfuric leach solution consisted of Zr(IV), Nb(V), Hf(IV), Al(III), and Fe(III). It was found that ordinary metal hydroxide precipitation was not feasible for obtaining a relatively pure product due to the co-precipitation of Al(III) and Fe(III). In this reported study, a basic zirconium sulfate precipitation method was investigated to recover Zr from a sulfuric acid leach solution of a eudialyte residue after rare earth elements extraction. Nb precipitated preferentially by adjusting the pH of the solution to around 1.0. After partial removal of SO42− by adding 120 g of CaCl2 per 1L solution, a basic zirconium sulfate precipitate was obtained by adjusting the pH to ~1.6 and maintaining the solution at 75 °C for 60 min. Under the optimum conditions, the loss of Zr during the SO42 removal step was only 0.11%, and the yield in the basic zirconium sulfate precipitation step was 96.18%. The precipitate contained 33.77% Zr and 0.59% Hf with low concentrations of Fe and Al. It was found that a high-quality product of ZrO2 could be obtained from the basic sulfate precipitate. 

  • 44.
    Ma, Yiqian
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Svärd, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Xiao, Xiong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Gardner, James M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Olsson, Richard
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Precipitation and crystallization used in the production of metal salts for Li-ion battery materials: A review2020In: Metals, ISSN 2075-4701, Vol. 10, no 12, article id 1609Article, review/survey (Refereed)
    Abstract [en]

    Li-ion battery materials have been widely studied over the past decades. The metal salts that serve as starting materials for cathode and production, including Li2CO3, NiSO4, CoSO4 and MnSO4, are mainly produced using hydrometallurgical processes. In hydrometallurgy, aqueous precipitation and crystallization are important unit operations. Precipitation is mainly used in the processes of impurity removal, separation and preliminary production, while controlled crystallization can be very important to produce a pure product that separates well from the liquid solution. Precipitation and crystallization are often considered in the development of sustainable technologies, and there is still room for applying novel techniques. This review focuses on precipitation and crystallization applied to the production of metal salts for Li-ion battery materials. A number of novel and promising precipitation and crystallization methods, including eutectic freeze crystallization, antisolvent crystallization, and homogeneous precipitation are discussed. Finally, the application of precipitation and crystallization techniques in hydrometallurgical recycling processes for Li-ion batteries are reviewed.

  • 45.
    Mukherjee, Deepjyoti
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Larsson, Henrik
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Odqvist, Joakim
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Simulating Diffusion Induced Grain Boundary Migration in Binary Fe-Zn2022In: Metals, ISSN 2075-4701, Vol. 12, no 10, article id 1632Article in journal (Refereed)
    Abstract [en]

    A recently developed phase-field model for simulating diffusion-induced grain boundary migration (DIGM) is applied to binary Fe-Zn. The driving force for the boundary migration is assumed to come from the coherency strain energy mechanism suggested by Sulonen. The effect of the angle of the grain boundary with the surface on the velocity of the boundary migration is studied in detail. The simulation results compare favorably with experimental observations, such as the oscillatory motion of the grain boundary, velocity of the moving grain boundary during DIGM, and the maximum value of mole fraction of Zn at the surface after 20 h of heat treatment.

  • 46. Ni, P.
    et al.
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Zhang, T. -A
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Effect of immersion depth of a swirling flow tundish SEN on multiphase flow and heat transfer in Mold2018In: Metals, ISSN 2075-4701, Vol. 8, no 11, article id 910Article in journal (Refereed)
    Abstract [en]

    The effect of the immersion depth of a new swirling flow tundish SEN (Submerged Entry Nozzle) on the multiphase flow and heat transfer in a mold was studied using numerical simulation. The RSM (Reynolds Stress Model) and the VOF (Volume of Fluid) model were used to solve the steel and slag flow phenomena. The results show that the SEN immersion depth can significantly influence the steel flow near the meniscus. Specifically, an increase of the SEN immersion depth decreases the interfacial velocity, and this reduces the risk for the slag entrainment. The calculated Weber Number decreases from 0.8 to 0.2 when the SEN immersion depth increases from 15 cm to 25 cm. With a large SEN immersion depth, the steel flow velocity near the solidification front, which is below the mold level of SEN outlet, was increased. The temperature distribution has a similar distribution characteristic for different SEN immersion depths. The high temperature region is located near the solidification front. Temperature near the meniscus was slightly decreased when the SEN immersion depth was increased, due to an increased steel moving distance from the SEN outlet to the meniscus.

  • 47.
    Ni, Peiyuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Zhang, T. -A
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Numerical study on the influence of a swirling flow tundish on multiphase flow and heat transfer in mold2018In: Metals, ISSN 2075-4701, Vol. 8, no 5, article id 368Article in journal (Refereed)
    Abstract [en]

    The effect of a new cylindrical swirling flow tundish design on the multiphase flow and heat transfer in a mold was studied. The RSM (Reynolds stress model) and the VOF (volume of fluid) model were used to solve the steel and slag flow phenomena. The effect of the swirling flow tundish design on the temperature distribution and inclusion motion was also studied. The results show that the new tundish design significantly changed the flow behavior in the mold, compared to a conventional tundish casting. Specifically, the deep impingement jet from the SEN (Submerged Entry Nozzle) outlet disappeared in the mold, and steel with a high temperature moved towards the solidified shell due to the swirling flow effect. Steel flow velocity in the top of the mold was increased. A large velocity in the vicinity of the solidified shell was obtained. Furthermore, the risk of the slag entrainment in the mold was also estimated. With the swirling flow tundish casting, the temperature distribution became more uniform, and the dissipation of the steel superheat was accelerated. In addition, inclusion trajectories in the mold also changed, which tend to stay at the top of the mold for a time. A future study is still required to further optimize the steel flow in mold.

  • 48.
    Pirouznia, Pouyan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing. Dalarna Univ, Dept Mat Sci & Engn, SE-79188 Falun, Sweden.;Voestalpine Precis Strip AB, Res & Dev Dept, SE-68428 Munkfors, Sweden..
    Andersson, Nils A. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    The Impact of the Gas Inlet Position, Flow Rate, and Strip Velocity on the Temperature Distribution of a Stainless-Steel Strips during the Hardening Process2019In: Metals, ISSN 2075-4701, Vol. 9, no 9, article id 928Article in journal (Refereed)
    Abstract [en]

    A non-uniform temperature across the width of martensitic stainless-steel strips is considered to be one of the main reasons why the strip exhibits un-flatness defects during the hardening process. Therefore, the effect of the gas inlet position in this process, on the temperature distribution of the steel strip was investigated numerically. Furthermore, an infrared thermal imaging camera was used to compare the model predictions and the actual process data. The results showed that the temperature difference across the width of the strip decreased by 9% and 14% relative to the calculated temperature and measured values, respectively, when the gas inlet position was changed. This temperature investigation was performed at a position about 63 mm from the bath interface. Moreover, a more symmetrical temperature distribution was observed across the width of the strip. In addition, this study showed that by increasing the amount of the hydrogen flow rate by 2 Nm(3)/h, a 20% reduction of temperature difference across the width of strip was predicted. Meanwhile, the results show that the effect of the strip velocity on the strip temperature is very small.

  • 49.
    Pirouznia, Pouyan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Dalarna Univ, Dept Mat Sci & Engn, SE-79188 Falun, Sweden.;Voestalpine Precis Strip AB, Res & Dev Dept, SE-68428 Munkfors, Sweden..
    Andersson, Nils A. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    An investigation of the Temperature Distribution of a Thin Steel Strip during the Quenching Step of a Hardening Process2019In: Metals, ISSN 2075-4701, Vol. 9, no 6Article in journal (Refereed)
    Abstract [en]

    The dimension quality of the strip within the hardening process is an essential parameter, which great attention needs to be paid. The flatness of the final product is influenced by the temperature distribution of the strip, specifically across the width direction. Therefore, based on physical theories, a numerical model was established. The temperature of the strip for the section before the martensitic transformation was objected in the predicted model by using a steady state approach. In addition an infrared thermal imaging camera was applied in the real process in order to validate the results and to improve the boundary conditions of the numerical model. The results revealed that the temperature of strip decreased up to 250 degrees C within the area between the furnace and the quenching bath. This, in turn, resulted in significant temperature difference across the width of the strip. This difference can be up to 69 degrees C and 41 degrees C according to the numerical results and thermal imaging data, respectively. Overall, this study gave a better insight into the cooling step in the hardening process. In addition, this investigation can be used to improve the hardening process as well as an input for future thermal stress investigations.

  • 50. Qian, Zhao
    et al.
    Guo, Weimin
    Jiang, Guanzhong
    Xu, Shaokun
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univ, Sweden.
    Liu, Xiangfa
    Revisiting Mg-Mg2Ni System from Electronic Perspective2017In: Metals, ISSN 2075-4701, Vol. 7, no 11, article id 489Article in journal (Refereed)
    Abstract [en]

    Both Mg and Mg2Ni are promising electrode materials in conversion-type secondary batteries. Earlier studies have shown their single-phase prospects in electro-devices, while in this work, we have quantitatively reported the electronic properties of their dual-phase materials, that is, Mg-Mg2Ni alloys, and analyzed the underlying reasons behind the property changes of materials. The hypoeutectic Mg-Mg2Ni alloys are found to be evidently more conductive than the hypereutectic Mg-Mg2Ni system. The density functional theory (DFT) calculations give the intrinsic origin of electronic structures of both Mg2Ni and Mg. The morphology of quasi-nanoscale eutectics is another factor that can affect the electronic properties of the investigated alloy system; that is, the electrical property change of the investigated alloys system is due to a combination of the intrinsic property difference between the two constituting phases and the change of eutectic microstructures that affect electron scattering. In addition, regarding the Mg-Mg2Ni alloy design for device applications, the electronic property and mechanical aspect should be well balanced.

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